I've owned both iPhones and Android phones, and setup both for my customers.

Both Android and Apple devices can fulfil mostly the same functions, but they look different to each other, and you click in different places to get things done. There are different apps for the same functions. Both app stores have hundreds of thousands of apps.

Apple iOS
Apple is more expensive. Apple locks you into their ecosystem, and gives you little choice. You can only use their devices, and they don't let you replace their stock apps with alternatives. Apple devices do not have expandable memory or removable batteries.You get what you are given, basically.

Google Android
Android lets you choose the device you want, from many manufacturers, and you can replace any part of the system, including the whole system itself. Most Android phones let you remove the battery and have memory card expansion. There are many more Android devices being sold every day, than Apple devices,

Conclusion
If you want choice, or like playing with custom roms, go for Android. Apple devices work, too, so if you like them, go for it. Just be aware you are getting locked into a small, expensive ecosystem.

Extra note
iCloud can be really flaky. Fortunately you can use Google to sync contacts, calendars, and emails on both Android and iOS. Dropbox is still the best photo and video auto-upload app.

XDA Developers was founded by developers, for developers. It is now a valuable resource for people who want to make the most of their mobile devices, from customizing the look and feel to adding new functionality.Are you a developer?